When sharks do attack people, it is probably because they mistake people for seals or other large ocean animals that they would like to eat. There are over 350 kinds of sharks, but only about 25 of those have ever been known to attack humans. Not all sharks are dangerous to humans, either. However, most kinds of sharks grow to about 5-7 feet long, which is about the same height as an average adult. Many sharks eat near the surface of the water, but will also dive down deeper in search of food. They have an excellent sense of smell, which helps them find food. They eat bony fish, squid, marine mammals, and even sea turtles. They don’t even need to chew their food! Sometimes sharks lose teeth, but when they do, new ones grow in their place. Sharks have several rows of sharp pointed teeth and powerful jaws to tear off big pieces of food, which they swallow whole. As they swim, water passes over the gills and oxygen flows in from the water. Sharks have gills on each side of their heads. They are cold-blooded and breathe through gills instead of through lungs. Even though they don’t have bones, sharks do have lots of other similarities to bony fish. Cartilage is the same stuff that makes your ears and the tip of your nose have their shape and be a little bit flexible. Their skeletons are made up of cartilage instead of bones. Sharks look a lot like marine mammals, but they are actually fish! Unlike most fish though, sharks do not have bones. Can you think of any other animals that are called fish but do not have the things it takes to be a real fish? Sharks Some examples are cuttlefish (they are mollusks, see below), jellyfish (they are actually plankton), and starfish (they belong to a group called “echinoderms”). Some animals that have the word “fish” in their names are not really fish. If it wants to swim deeper, it lets some air out and if it wants to swim up towards the surface, it will let more air into its swim bladder. The fish can adjust how much air is in its swim bladder. Air inside the swim bladder helps the fish float through the water. Most fish have a special part inside their bodies called a swim bladder. A person who studies fish is called an ichthyologist (say: ICK-THEE-ALL-O-JIST). Most fish are covered with small scales instead of skin. They cannot breathe air or live outside of water. (Cold-blooded means that their body temperature depends on the temperature of the water around them, unlike humans, who have a normal body temperature that stays at 98.6 degrees.) They breathe oxygen from the water through gills on the sides of their bodies. Fishįish have bones and are cold-blooded. Other fish think the lure is food, but when they try to eat it, the anglerfish eats them instead! Here is a picture of an anglerfish. It has a glowing “lure” that extends from its head and dangles above its mouth. The anglerfish is an example of a deep sea creature that uses bioluminescence to find food. These “night lights” help them with navigation, finding food, and finding mates. Therefore, they must make their own light. Many bioluminescent animals live far down in the oceans where it is very dark (sunlight penetration declines in deep water). The light is called bioluminescence and happens when certain chemicals mix together, along with some oxygen from the water, in a particular part of the animal’s body. Some creatures that live in the ocean use a special chemical reaction inside their bodies to create a glowing light. They eat plankton and are eaten by larger animals, such as whales and birds. Krill are small creatures that look like shrimp. They drift along with the currents in the water and are eaten by fish, scallops, anemones, and others. Plankton are crucial to the life of the ocean because they are a food source (as primary producers) for a lot of animals. This warm, “sunlight zone” enables photosynthesis, a process in which light energy is converted into chemical energy. Microscopic plants and animals called plankton live on the surface of the ocean. A person who studies ocean life is called a marine biologist. The ocean is also filled with lots of plants, which provide food, homes, and protection for ocean animals. Oceans cover more than two thirds of the earth’s surface, and they are very deep!įish and other animals make their homes in all different parts of the ocean, even on the bottom, or sea floor. Then, when you’re done with that, imagine yourself as an ocean animal for the day–details below! Ocean Animals Science Lesson Ocean Life One thing these animals never have to worry about, though, is the ocean freezing.Ĭheck out the first experiment below to find out. Some are microscopic, others are massive. Some are predictable, others have strange habits and weird abilities. Some are beautiful, others are funny looking. Ocean animals come in almost every shape and size imaginable.
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